Pyrolytic ovens are in common usage today and the self-cleaning feature thereof requires that the oven door be safely latched while the oven is at extemely high temperatures during a so-caled self-cleaning period, and that the latch remain unreleasable until the oven has cooled to a predetermined temperature.
In some pyrolytic or self-cleaning ovens, a bimetallic coil, which is responsive to the temperature in the oven, moves a pawl or dog into a blocking position with respect to a latch to thereby prevent the latch from moving from a latched position to an unlatched position after the bimetallic strip senses temperatures above a predetermined level. Such a device is disclosed in U.S. Pat. Nos. 3,438,666 and 4,133,337.
The bimetallic coil is, of course, sensitive to the heat in the oven, whether it is in a self-cleaning mode or in any heating mode, and will move the blocking pawl towards a blocking position. It is also possible to lock it inadavertently during an extended bake cycle. If the user of the oven places the oven in a bake mode at an elevated temperature for an extended period of time, the locking dog may move to a position which would block the movement of the handle from the latched position to the unlatched position.
A problem is presented by the possibility that, during an extended baking cycle, a child, or perhaps other person, may inadavertently move the latching handle to a latched position. This may be possible because the latch may be cammed past the locking pawl and then the latch will be blocked from unlatching by the locking pawl until the oven temperature falls to a level such that the bimetallic element will move the locking pawl away from a blocking position. This can have deleterious effects on the contents of the oven which are being subjected to baking, in that the oven door cannot be opened at a desired time, and the contents of the oven will continue to bake, perhaps resulting in a burned condition or in any event, an overcooked condition.
Accordingly, it is an object of the present invention to provide a new latching and blocking mechanism such that the latch cannot be moved to the latched position from an unlatched position if the locking dog under the control of the bimetallic element has moved to a position in which the locking dog would lock the latch if the latch is not inadvertently set.
A specific object of this invention is to provide an improved latch for pyrolytic ovens and the like which prevents inadvertent latching of the oven door when it is not in a self-cleaning mode.